Method and apparatus for grinding and lapping



Feb. 24, 1948. J. c. WILSON 2,436,466

METHOD AND APPARATUS FOR GRINDING AND LAPPING Filed Sept. 27, 1945 s Sheets- Sheet 1 luvsuron- A m/mew Feb. 24, 1948. J. c. WILSON METHOD AND APPARATUS FOR GRINDING AND LAPPING Filed Sept. 27, 1945 3 Sheets-Sheet 2 Inven for JOHN C. W! LSoN,

By 1 J 5 Alfarncys METHOD AND APPARATUS FOR GRINDING AND LAPPING 3 Sheets-Sheet 3 Filed Sept. 27, 1945 INVENTOR Jul/v 6'. WILSON, a i

lirron Patented Feb. 24, 1948 .PATE

FFICE Mnrnon AND APPARATUS FOR GRINDING AND LAPPING John C. Wilson, Springfield,

Ohio, assignor to The Thompson Grinder Company, Springfield, Ohio, a corporation of Ohio 9 Claims.

This invention relates machines and methods and is particularly conpiece is ground in one machine and lapped in another. This involves two set-ups of the workpiece in a machine with the attendant loss of time and labor and introduces the possibility that the workpiece will be incorrectly sized. Also, two machines are required thus necessitating a greater investment than if only one device were necessary.

Accordingly, the particular object of this invention is to provide a method and apparatus for both grinding and lapping workpieces at one set-up and with the same abrasive member.

Another object is to provide a support for the grinding wheel which is operable for lapping a workpiece when the surface speed of the wheel is reduced.

A still further object is to provide a method and apparatus for producing workpieces on a grinding machine which have superior surface finishes thereon.

These and other objects and advantages become more apparent upon reference to the following specification taken together with the accompanying drawings in which:

Figure 1 is a perspective view of a grinding machine constructed according to this invention:

Figure 2 is a section taken substantially along the line 2, 2 of Figure 1 showing more in detail the construction of the spindle and the grinding wheel support;

Figure 3 is an enlarged sectional view through the grinding wheel and the support therefor of this invention;

Figure 4 is a diagrammatic view illustrating the motor means for reciprocating the wheel and also for reciprocating the work; I

Figure 5 is a diagrammatic view illustrating the path of the grinding wheel when grinding a workpiece, and

Figure 6 is a view similar to Figure 5 but show- 'ing the path of the wheel when the workpiece is being lapped.

General arrangement A grinding machine constructed according to this invention has a grinding wheel and a 'W01'kpiece supporting means which are relatively "movable in at least two directions. The relative movement is utilized for traversing the wheel and workpiece for grinding the required area of the latter.

The grindingwheel support according to this invention comprises resilient means disposed between the wheel and its supporting shaft. Then, when the wheel is driven at grinding speed, say, at a surface speed of about 6,000 feet perminute, the wheel support is substantially rigid and a true grinding operation takes place. However, if the surface speed of a grinding wheel is reduced to only a few hundred feet per minute, then the resiliency of the wheel support becomes eitective and the grinding wheel acts as anabrasive lapping member. By rapidly oscillating the wheel axially relative to the workpiece, when the wheel is operating at low speeds, the entire surface of the workpiece may be lapped to a high finish and to a high degree of accuracy.

Structural arrangement Referring to Figure 1, there is shown a grinder having a bed I0 u on which a workpiece l4.

18 on vertically disposed ways. Mechanism such as the screw 20 and hand wheel '22 may be pro- Vided for reciprocating this saddle on the column It. Transversely reciprocable in the saddle it is a wheel head 2 4 that is carried on the ways 2 'i.

Reference to Figure 2 will show that the wheel head 24 carries a motor'28, the shaft 30 of which extends leftwardly through the wheel head to support a grinding wheel 32. According to this invention there is provided a resilient member such as the rubber-like annular sleeve 35 between the wheel 32 and the-shaft 39. The ring 35 may be secured in any suitable permanent manner with the hub 36 that attaches to the shaft 3 and to the flanged wheel receiving ring 33, the latter being provided with the annular plate ti! which secures the wheel on the said ring.

The shaft 30 may be journalled in the precision adjustable sleeve bearings '42 adjacent the wheel and the precision anti-friction bearings-a l at the opposite end of the said shaft. A wheel guard 46 may be provided for guarding the operator against sparks and chips.

The wheel head israpidly recipro'cable parallel to the wheel spindle axis in the ways 26 by a motor 48 which is carried in the saddle and whose plunger 50 is attached to the wheel head by the lug 52. The motor 48 is preferably flu d operable and may be controlled by a valve 54. The valve may, in manners well-known to those skilled in the art, the reciprocation of rapid axial oscillation The table 12 may be reciprocate'd by a motor 56 carried in the machine bed Ill and whose plunger is connected with the said table by a lug 58, The motor 56, like the motor 48, may be controlled in any of several well-known manners for driving the table in either direction and at any predetermined speed. It will be apparent that the motors 4B and 56 provide means for relatively reciprocating the workpiece and grinding wheel in two directions while the screw 20 provides a means for relative reciprocation thereof in a third direction.

be automatically actuated by the wheel head to effect the of the wheel 32.

Operation In operation, the workpiece I4 is secured either to the table I2 or to any suitable workpiece carrying device mounted thereon.

A grinding operation is carried out by reciprocating the table l2 relative to the wheel and, if the width of theworkpiece requires, gradually, and preferably intermittently, moving the wheel transversely over the workpiece. Such an operation is diagrammatically indicated in Figure 5.

After the workpiece has been ground down to a predetermined point, the surface speed of the wheel is slowed down from its grinding speed of about 6,000 feet per minute to a few hundred feet per minute. The workpiece and wheel are then brought into engagement under a moderate pressure, and the wheel is rapidly oscillated transversely relative to the workpiece by the motor 3 while the motor 58 is actuated relatively slowly to pass the workpiece beneath the wheel. This operation is diagrammatically illustrated in Figure 6 where it can be clearly seen the fine pitch oscillatory path A is produced by the rapid axial reciprocation of the wheel 32 by the motor 48 and the movement of the work table by the motor 56. It is to be further noted that the reversal of axial reciprocatory movement of the wheel at B .is arranged to take place substantially instantly so that the passage of the wheel, as indicated at C, over the work surface will at all times be in a direction substantially-perpendicular to the lines of grinding scratches produced in the work surface, these grinding scratches being parallel to the lines of feed travel D indicated in Figure 5. Thus, under these conditions of operation, the abrasive action will be roughly at right angles to the peaks and ridges produced in the prior grinding operation with the same wheel which makes for efficient abrading action not obtainable in methods where the cutting is substantially parallel to these peaks and ridges.

During the lapping operation, the resilient ring 34 serves to yieldably urge the wheel against the workpiece maintaining proper working pressure and correct seat of the wheel against the workpiece and to provide a true lapping action thereof whereby the high spots, peaks, and ridges of the workpiece are most effectively cut off and a high surface finish is obtained. The resilient wheel mounting fully protects the grinding and lapping wheel from vibration of the machine and makes practical the rapid reversal of axial reciprocating movement shown in Figure 6 so that the wheel may effect the lapping operation on the workpiece.

It will be apparent that the practice of the methods of this invention and the use of the apparatus thereof will produce workpieces having a superior surface finish and which are precisely size-d. Furthermore, this may be accomplished in a single machine and at one setup.

It will be understood that various modifications and arrangements in structure could be made without departing from the spirit of my invention and, accordingly, I desire to comprehend such modifications and substitutions of equivalents as may be considered to come within the scope of the appended claims.

I claim:

1. The method of forming workpieces in a grinding machine which comprises; relatively reciprocating the workpiece and wheel in one direction while rotating the grinding wheel at grinding speed; and thereafter rapidly axially reciprocating the wheel and slowly reciprocating the work in perpendicular directions while rotating said wheel at substantially less than grinding speed.

2. The method of forming workpieces by a grinding wheel which comprises; resiliently supporting the said wheel on a drive shaft; driving the said wheel at grinding speed; relatively reciprocating the wheel and workpiece in a direction perpendicular to the grinding wheel axis; reducing the speed of the wheel to substantially less than grinding speed; and simultaneously slowly relatively reciprocating the wheel and workpiece perpendicular to said axis and rapidly axially reciprocating said wheel to effect a cutting action of said wheel on said workpiece in a substantially normal direction to the direction of said first mentioned relative reciprocation of wheel and workpiece.

3. In a method of forming workpieces by a grinding wheel; yieldably supporting the said wheel; driving the wheel at grinding speed; reciprocating the workpiece relative to the wheel for grinding the former; reducing the speed of the wheel to substantially less than grinding speed; and again reciprocating the workpiece relative to the wheel while rapidly axially oscillating the wheel for lapping the former to trace a path on said workpiece substantially perpendicular to the direction of workpiece reciprocation.

4. In a method of grinding and lapping workpieces with a single grinding wheel; resiliently supporting and driving said wheel; traversing the workpiece in a straight path while the wheel is operating at grinding speed; and thereafter continuing the traversing of the workpiece and rapidly axially reciprocating the grinding wheel to efiect an oscillatory path of relative work and wheel travel substantially perpendicular to said traversing movement while the wheel is runnin at substantially less than grinding speed.

5. In a grinding machine; a work supporting means; means for reciprocating said means; a grinding wheel having a drive shaft; means comprising a substantially annular resilient member yieldably connecting said wheel with said drive shaft; means for driving said wheel at high and low speeds; and means for rapidly reciprocating said wheel and moving said work supporting means to cause said wheel to trace an undulating path of sharp reversals substantially perpendicular to the movement of said work supporting means.

6. In a grinding machine adapted for both grinding and lapping a workpiece; workpiece supporting means including a reciprocable table and a first motor means for reciprocating said table; a grinding wheel and a drive shaft therefor and a second motor means for rapidly reciprocating said shaft and wheel in an axial direction substantially perpendicular to the direction of reciprocation of said workpiece supporting means; means comprising a resilient hub securing said wheel to said drive shaft; and means for driving said wheel at a high surface speed to effect a grinding operation and at a low surface speed to effect a lapping operation of said wheel on said workpiece.

7. In a combined surface grinder and surface lapping machine utilizing a common abrasive wheel for performing grinding and lapping operations, the combination of a machine frame, a work table reciprocatable on said frame, a saddle vertically movable on said frame, a wheel head mounted for horizontal movement on said saddle transverse to the reciprocatory movement of said table, a grinding wheel spindle journaled in said wheel head having its axis extending perpendic ular to said work table reciprocation and parallel to said wheel head reciprocation, a resilient mounting hub on said spindle, a grinding wheel mounted on said resilient mounting means, a hydraulic cylinder interconnected between said frame and said work table to effect reciprocation thereof, a second hydraulic cylinder carried in said saddle and connected to said wheel head to effect reciprocation thereof, adjusting means for radially moving said spindle and Wheel into relative adjustment with a work piece on said Work table, and means for at one time rotating said grinding wheel at grinding speed and'intermittently axially moving said spindle carrier in synchronism with the reciprocation of said table and at another time rapidly reciprocating said wheel spindle axially independent of the reciprocation of said work table, said means including a hydraulic control valve operable by the reciprocation of said wheel head.

8. In a grinding machine; a reciprocable work supporting means; a grinding wheel having a drive shaft; resilient means supporting said means for axially said wheel and shaft; and means tive to said Work table, means interconnecting a grinding wheel, resilient said grinding wheel to reciprocating said wheel spindle in axial direction, means for selectively driving said Wheel at a high rotative speed or at low rotative speed, and means for radially adjusting said grinding wheel and spindle to predetermined positions relative to said work table.

JOHN 0. WILSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 528,726 Hyde Nov. 6, 1894 1,790,446 Suhner Jan. 27, 1931 1,914,647 Raule June 20, 1933 2,022,542 Flygare et a1 Nov. 26, 1935 2,033,395 Peaslee Mar. 10, 1936 2,127,210 Dunbar Aug 16, 1938 2,171,892 Richardson Sept, 5, 1939 2,239,091 Flygare Apr. 22, 1941 2,276,625 Patrick Mar. 17, 1942 2,378,903 Baldenhofer June 26, 1945 FOREIGN PATENTS Number Country Date 745,444 France Feb. 14, 1933 

